The present invention relates to data storage, and more specifically, the present invention relates to divisionally managing a file on a user basis in a file system in which data in a medium is handled as a file.
A file system is intended to control reading from and writing to a tape cartridge (medium) mounted in a tape storage apparatus (tape drive). The Linear Tape File System (LTFS) is a file system used in tape drives, which uses a magnetic tape medium housed in a tape cartridge as a removable data storage medium.
LTFS is responsible for controlling a tape library, which stores a plurality of tape media. With LTFS, an application does not have to have knowledge of the tape library, and a tape device may be more readily used than in conventional tape libraries operating under some other file system. Since magnetic tape has the characteristics of having a large capacity and low cost, a use case is possible in which a tape device is used as storage for a cloud system. In the case where LTFS is used in a cloud system including the tape library (as a storage system), it is desirable that a plurality of users manage access to the data on any one magnetic tape. However, in LTFS as used conventionally, files are managed with an index (metadata) with the assumption that a magnetic tape is allocated to one user only.
LTFS supports a plurality of operating systems, and therefore does not store information about who is the owner of each file in a magnetic tape itself. Therefore, it is difficult for a tape library running LTFS to manage access to the files in the magnetic tape on a user basis. In order to manage the files on a user basis, the files have to be systematically managed on the cloud side of the cloud system.
Japanese Patent Application No. JP10-232800A discloses a technique of dividing data itself, according to which data in one tape cartridge is divided into a plurality of tape cartridges, which may be used by a plurality of users. However, this reference does not disclose a system environment in which a plurality of users are allowed to share one medium, with each user having file attribute information for the files on the medium.